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Phragmidium bulbosum

Blackberry rust diseases

Description

Phragmidium bulbosum is a rust fungus associated mainly with blackberries (Rubus fruticosus). It completes its life cycle on the same host, overwintering as teliospores on stems and fallen leaves. During the growing season spermogonia, aecia, uredinia, and telia are produced, predominantly on the leaves, but sometimes also on petioles and young shoots. The species is distributed across much of Europe, especially in humid habitats. Heavy infections can lead to premature defoliation, which weakens plants and reduces fruit production, although the overall impact is usually moderate. It can be confused with Phragmidium rubi-idaei, but that species occurs on raspberry and differs in spore morphology and host range.

Symptom

Orange, later brown sports develop on the upper leaf surface; orange uredinia and later dark/black telia form mainly on the lower side, causing spotting and leaf drop.

Tree Species: Blackberry

Part of a plant- attacked: Tree trunk, Leaf / Needle, Fruit / Seed, Branch

Pest significance: Harmful

Pest Category: Fungi

Invasive Species: No

Present in EU: Yes